It is known how to feed a material to be treated, for drying, for killing off micro-organisms or for popping, on a conveyor belt or a fluidization bed in the longitudinal direction through a microwave waveguide and then heating the material to be treated. Particularly in the case of drying it has been shown that in the case of treatment of a pourable material local overheating with scorching can occur when working with higher microwave energy densities. Consequently, up to the present time, drying has had to be undertaken at low power of the microwave generator and, therefore, with lesser drying output (kilograms of dried product per unit of time).
The present invention takes upon itself the task of achieving an essentially greater output than was previously possible when treating bulk materials with the aid of microwaves.